The great outdoors in Hong Kong will no longer be a haven from your mobile phone, with three new base stations expected to provide coverage to almost every corner of the city's country parks and hiking trails.

Francis Chan Wai-ming, Ofta's senior telecommunications engineer, said the telecoms authority would build another three base stations in remote areas to improve mobile-phone coverage in southwestern Lantau and northeast New Territories.

Mr Chan said the city's mobile service network already covered about 95 per cent of hiking trails. The new base stations would enhance coverage in the other 5 per cent.

However, blind spots and corners without coverage would still exist. 'There are still some hidden areas which will be really difficult to cover,' Mr Chan said.

'But this problem occurs not just on country trails but in urban areas. Usually if users move a few steps or on to higher ground, they will receive phone signals.'

The number of digital maps on Ofta's website outlining the quality of mobile-phone coverage on popular country hiking trails has risen from 99 in 2006 to 161 now.

Three colours on the maps indicate mobile-phone coverage.

Green indicates the signal of at least one mobile network is good. Yellow indicates the voice quality of calls may be poor. And red indicates there is no network coverage.

The authority reminded hikers that they should not rely solely on mobile phones to seek emergency help.

It suggested hikers use walkie-talkies operating at 409 megahertz for short-range communication.

Kennedy Wong Tang-kin, a Government Flying Service aircrewman, said the service had conducted about 500 countryside rescues annually over the past three years.

He said the figures were still high and hikers should be more alert to safety during hikes.

A spokesman for the Civil Aid Service said it had taken part in 54 rescue operations in the first nine months of this year, and expected to see an increase this year on its 73 operations last year. Over the same period the Fire Services Department has been called to 103 countryside rescues involving 225 people. Five of the cases involved deaths.